I was trying to run
sudo apt-get upgrade
in terminal today, and I received the message here encountered by OP
As a solution, I ran both of Pensacola's commands in terminal. It didn't seem to do anything on my computer, so I restarted my computer. As normal, I faced the GRUB screen, and chose to log into Ubuntu. However, instead of the login menu disappearing and immediately followed by the Ubuntu load circle that then asks me to put in my password, the login menu just disappears and I am left at a gray screen. I'm not sure what is up though it certainly seems connected to what I ran before. Does anyone know how I can fix this?
Regarding my system, I have:
Processor: - AMD Ryzen 5 1500 X Quad-Core Processor x 8 - Graphics: GeForce GTX 1050 Ti/PCIe/SSE2 - Base system: Ubuntu 16.04.2 LTS 64-bit - GNOME Shell